The eLOV::mLexA::p65 driver is a light-activated transcriptional activator ('driver') designed for use in a binary expression system. It is a fusion protein composed of 'eLOV' (an 'evolved' version of the flavin binding domain (LOV2) and carboxy-terminal helical extension (Jα) of the Avena sativa Phototropin 1 (PT1) gene), a Tag:NLS(SV40-largeT) nuclear localization signal (NLS), the tdTomato fluorescent protein, and a lexA::p65 driver in which the NLS-like sequence of lexA has been inactivated by mutation. In the dark, the eLOV domain cages the Tag:NLS(SV40-largeT) sequence, and the fusion protein shows little or no transcriptional activator activity. In response to blue light, a conformational change in the eLOV domain uncages the Tag:NLS(SV40-largeT) sequence, allowing the protein to enter the nucleus and activate transcription of a transgene expressed under the control of lexAop regulatory sequences (FBrf0254643).